The present invention relates to prostheses for treatment of aneurysms, arterio-venous fistulas, obstructive vascular disease and other applications. More specifically, the present invention relates to prostheses including coiled sheet portions having a biocompatible material affixed thereto which may be used in a variety of applications as an internal bandage.
Millions of people worldwide are afflicted each year with vascular diseases, ranging from vascular obstructive disease, such as arteriosclerosis, to diseases that weakened the arteries or other vessels, resulting in potentially fatal aneurysms and arterio-venous fistulas. Arterio-venous fistulas commonly occur other than by progression of natural disease, for example, as a result of accidents and gun-shot wounds. Each of these diseases has lead to the development of specialized treatments ranging from minimally-invasive techniques to more conventional open surgical techniques.
For example, a health problem afflicting an older segment of the population is the occurrence of disease that weakens the arteries and other body vessels, developing into aneurysms that may rupture, often with fatal consequences. A conventional treatment of aneurysms, especially those occurring in the abdominal aorta, has involved invasive surgery to resect and remove the diseased body vessel and replace it with either a native vessel, harvested from elsewhere in the body, or a synthetic graft material. Such treatments typically pose a major risk to the patient""s health, and frequently cannot be undertaken at all, if (as is common) the patient is in poor health.
A number of vascular prostheses have therefore been developed that permit a synthetic graft to be placed transluminally within the aneurysm, to isolate the aneurysm from fluids flowing in the body vessel and which relieve pressure from the aneurysm.
These previously known vascular prostheses generally anchor a tubular synthetic graft inside the body vessel, on either end of the aneurysm, using a stent, as described, for example, in U.S. Pat. No. 5,078 to Kreamer and U.S. Pat. No. 5,219,355 to al.
Similarly, U.S. Pat. No. 5 Chuter and U.S. Pat. No. 5,275,622 to describe stent-graft combinations, deliver transluminally, comprising a tubular grai barbed self-expanding anchors secured by E ares to the ends of the tubular graft. U.S. Pat. No. 5,366,473 to Winston et al. describes a stent graft combination wherein a tubular graft has a self-expanding coiled sheet stent riveted to either end of the graft.
A drawback of the foregoing stent-graft systems is that they generally require a large access site (e.g., 16-22 Fr), which limits the applicability of such devices to larger vessels. Specifically, the graft material generally must be bunched or gathered to fit within the delivery system, as described in the above-mentioned Chuter, Winston et al. and Lazarus 10 patents, but cannot be compacted within the delivery system, or problems may arise relating to unfurling of the graft during deployment. In addition, clinical testing of previously-known stent-graft combinations has revealed problems with inadequate sealing between the graft material and the anchors, and where the graft contacts the body lumen proximally and distally of the aneurysm.
Other arrangements for isolating aneurysms are also known. U.S. Pat. No. 4,577,631 to Kreamer describes a method of gluing a graft across an aneurysm using a biocompatible adhesive. U.S. Pat. No. 4,617,932 to Kornberg describes a bifurcated graft that is engaged to a vessel wall using hooks. U.S. Pat. No. 5,575,817 to Martin describes a bifurcated graft where an extension is added to one of the legs of the graft after a main body of the graft has been deployed. U.S. Pat. No. 5,211,658 to Clouse describes a stent-graft combination wherein a temperature activated skeleton is first deployed in a body lumen so that it spans an aneurysm; a graft then is affixed to the deployed skeleton. U.S. Pat. No. 5,405,379 to Lane describes a polypropylene sheet which is rolled into a coil, and permitted to self-expand within the body lumen so that it spans the aneurysm. U.S. Pat. No. 5,100,429 to Sinofsky et al. describes a coiled sheet stent including a layer of collagen-based material which is heated by an energy source so that it fuses to form a rigid structure.
Each of the foregoing arrangements has inherent disadvantages peculiar to their designs that makes the use of such designs impractical. These disadvantages range from the mechanical complexity of the Kreamer, Clouse and Sinofsky et al. designs, to the inability to obtain an adequate seal at ends of the device, as in the Kornberg, Martin and Lane devices.
With respect to treatment of obstructive vascular disease, a number of prostheses have been developed for intraluminal deployment. These devices, of which the Palmaz-Schatz stent sold by Cordis Corporation, Miami Lakes, Florida, is typical, treat obstructive disease, for example, in the coronary arteries, by retaining the patency of vessel following an angioplasty procedure. Most previously known prostheses designed to treat obstructive disease include a plurality of throughwall openings to promote cellular proliferation. A drawback of such designs, however, is that the openings may also promote re-formation of the obstruction over time.
Previously known techniques for treating arterio-venous fistulas, which permit oxygenated blood to be shunted from an artery directly to the venous system, typically involve open surgery. Thus, for example, a gun-shot victim, given the present state of the art, must undergo surgery to repair an arterio-venous fistula. The present state-of-the art lacks any devices which may be readily deployed, even on an interim basis, to prevent excessive blood loss while awaiting surgery.
In view of the foregoing, it would be desirable to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that is simple in design and easily deployed.
It would further be desirable to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that overcomes problems associated with the bulkiness of prior art stent-graft systems, and that can be readily scaled for use in a variety of vessels, thereby enabling treatment of disease in even very small body lumens.
It would further be desirable to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that may be readily deployed in a bifurcated vessel.
It would still further be desirable to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that provides an internal bandage, for example, that can stem blood loss through an arterio-venous fistula, or provide a positive seal at the ends of a graft to reduce bypass flow.
In view of the foregoing, it is an object of the present invention to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that is simple in design and easily deployed.
It is another object of this invention to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that overcomes problems associated with the bulkiness of prior art stent-graft systems, and that can be readily scaled for use in a variety of vessels, thereby enabling treatment of disease in even very small body lumens.
It is a further object of the present invention to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that may be readily deployed in a bifurcated vessel.
It is a yet further object of the invention to provide a prosthesis for treating aneurysms, obstructive disease of vessels and body organs, and arterio-venous fistulas, that provides an internal bandage, for example, that can stem blood loss through an arterio-venous fistula, or provide a positive seal at the ends of a graft to reduce bypass flow.
These and other objects of the invention are accomplished by providing a prosthesis comprising a coiled sheet portion having biocompatible graft material affixed thereto, so that the graft material is at least partially wound within the coiled sheet portion when it is contracted to its delivery state. The graft material may comprise a sheet or tube that is affixed along a part or all of the circumference of the coiled sheet portion, and serves to alter flow to a portion of a body lumen in which the prosthesis is deployed. The graft may be affixed to an interior or exterior surface of the coiled sheet portion, or may comprise several layers. The prosthesis may be configured for use in a single or bifurcated organ or vessel.
In a preferred embodiment, the coiled sheet portion of the prosthesis comprises a mesh formed from a shape-memory alloy, such as a nickel-titanium alloy, that exhibits super-elastic behavior at body temperature. The coiled sheet preferably includes one or more rows of locking teeth along a longitudinal edge that interengage the mesh to retain the prosthesis at a desired expanded diameter. In addition, the mesh may include a plurality of radially outwardly directed projections along one or both ends that engage an interior surface of a body lumen.
The mesh of the coiled sheet may have a size suitable for use in smaller body arteries, such as the coronary arteries and carotid arteries, or may be scaled to accommodate larger vessels such as the abdominal aorta and iliac arteries. For larger vessels, the mesh of the coiled sheet may include articulations to assist in maneuvering the prosthesis through tortuous body passageways.
The graft material used in the prosthesis of Be the present invention may be either fluid impermeable, for example, for treating arterio-venous fistulas or semi-permeable, for example, to permit nourishment of vessel intima when treating occlusive vascular disease while reducing throughwall cell proliferation. The graft material may also be impregnated with one or more drugs to achieve to provide a desired effect. The graft material may also serve to reduce embolization of frangible material from the interior of body lumen following, for example, an angioplasty procedure.
In addition to the foregoing applications, a pair of prostheses constructed in accordance with the present invention may be advantageously employed, one at either end, for positively sealing the ends of a conventional tubular graft.
Methods of making and deploying the prosthesis of the present invention in single and bifurcated lumens are also provided. In accordance with these methods, the prosthesis is first deployed in a body lumen from a reduced delivery state. A dilatation element is then disposed within the prosthesis and expanded, thereby locking the prosthesis at an expanded diameter and positively sealing the graft material against the interior surface of the body lumen.